Component, especially a high-pressure component for fuel injection systems, and method for producing a component of this type

ABSTRACT

In a component, in particular a high-pressure part for a fuel injection system, having intersecting bores, at least one bore of the two intersecting bores is designed with a flat region, and the component has inherent compressive stresses in the area of the flat region of the bore. This yields an increase in strength of the component in the area of the intersection point of the two bores.

FIELD OF THE INVENTION

[0001] The present invention relates to a component and a method forproducing such a component.

BACKGROUND INFORMATION

[0002] The related art includes British Patent Nos. 2,322,919,2,322,920, 2,322,321 and 2,322,922 as well as German Published PatentApplication No. 198 08 894.

[0003] In conjunction with the present invention, a number of possiblecomponents which have intersecting bores in the interior, in particularCR injectors (CR=common rail) are of interest. Not only are thesecomponents under a very high internal pressure in the fuel injectionsystem, but also the internal pressure is subject to great periodicfluctuations (pulsating internal pressure), so they must meet highstrength requirements accordingly. The strength of the boreintersections is especially important.

SUMMARY OF THE INVENTION

[0004] An object of the present invention is to further increase thestrength of bore intersections in components of the aforementioned typewith respect to the internal compressive stresses that occur.

[0005] On the basis of the non-cutting shaping of the component inparticular by pressure acting from the outside, a controlled flatteningof the bore at the point of intersection of the respective bores can beachieved without any great technical complexity or cost expenditure.

[0006] The desired increase in the strength of the component is derivedthrough inherent compressive stresses produced in a controlled mannerdirectly at the most highly stressed point in the component, the boreintersections. Better utilization of the material is also achieved dueto the increased strength of the component at these locations, which areexposed to extreme loads.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 shows an embodiment of a CR injector shown in cross sectionwhere the component is still undeformed.

[0008]FIG. 2 shows the object from FIG. 1 shown in a cross-sectionaldiagram according to FIG. 1 (section II-II in FIG. 3) after non-cuttingshaping of the component.

[0009]FIG. 3 shows the object from FIG. 2 as seen in the direction ofarrow “A”.

[0010]FIG. 4 shows a slightly modified variant of a CR injector incomparison with FIGS. 1 through 3, shown in a cross-sectional diagramaccording to FIG. 1 or 2, where the component is still undeformed.

[0011]FIG. 5 shows the object from FIG. 4 shown in a correspondingcross-sectional diagram, but after non-cutting shaping of the component.

[0012]FIG. 6 shows a CR injector according to FIG. 1 in a correspondingcross-sectional diagram (section VI-VI in FIG. 7), with the female dieinserted.

[0013]FIG. 7 shows a section along line VII-VII in FIG. 6.

DETAILED DESCRIPTION

[0014]FIGS. 1 through 3 show an essentially cylindrical component 10which is part of the CR injector. In its prefabricated state as shown inFIG. 1, component 10 has a continuous bore 11 with a circular crosssection. A second bore 12 with a much smaller cross section opens at 13into first bore 11 at a right angle to it. FIGS. 1 and 2 show clearlythat central axes 14, 15 of two bores 11, 12 intersecting at 13 do notmeet at the center of component 10. Second bore 12 thus openseccentrically into first bore 11.

[0015]FIG. 2 shows that first bore 11 (still circular in the partiallyshaped state according to FIG. 1) has a flat region 16 in the area ofintersection 13 of two bores 11, 12. Flat region 16 is the intentionalresult of non-cutting shaping of component 10 produced by pressureacting from the outside (in the direction of arrow 17) via a rectangularram 18 (see FIG. 1).

[0016] As shown in FIGS. 2 and 3, this results in a groove-shapeddeformation 19 on the outer circumference of component 10, although itis limited only to the area of second bore 12 and its intersection 13with first bore 11, like flat region 16 produced by the pressure actingon it. Inherent compressive stresses thus build up in the area aroundintersection point 13, thereby greatly increasing the strength ofcomponent 10 in this area. The material area surrounding intersectionpoint 13 of two bores 11, 12 meets extremely high strength requirementsdue to the pulsating compressive stress caused by the liquid medium(e.g., fuel) flowing through the bores.

[0017] The component labeled 10 a in FIGS. 4 and 5 is similar in designto component 10 in FIGS. 1 through 3. In particular, like the latter, italso has a continuous bore 11 with a large diameter and a second bore 12with a much smaller diameter opening into the former eccentrically at aright angle. One difference in comparison with the embodiment accordingto FIGS. 1 through 3 is that in its processed state (FIG. 4), component10 a has a noncontinuous starting bore 20 which is directed atintersection point 13 of two bores 11, 12. To produce a local flatregion 21 of bore 11 directly at opening point 13 of bore 12 (see FIG.5), a ram 22 is inserted into starting bore 20 (see FIG. 4) and is actedupon by a force in the direction of arrow 23. Ram 22 may have a circularor oval cross section. With regard to the resulting increase in strengthin the area of intersection point 13, the statements made in this regardconcerning the embodiment according to FIGS. 1-3 are also applicablehere accordingly.

[0018] One particular feature of the variant according to FIGS. 6 and 7is that a female die labeled 24 on the whole is inserted into continuousbore 11 of component 10, which otherwise corresponds to the embodimentaccording to FIG. 1.

[0019] As shown in particular in FIG. 6, female die 24 is composed oftwo “halves” 25, 26 which are subdivided essentially horizontally and,when assembled, yield a circular cross section of female die 24corresponding to the cross section of bore 11. Upper half 26 of femaledie 24 has a trough-shaped recess 27 at intersection point 13 of twobores 11, 12.

[0020] If, according to the embodiment illustrated in FIGS. 1 through 3,component 10 is acted upon by pressure in the direction of arrow 17 dueto a ram 18 at the level of bore 12 (see FIG. 1), the material ofcomponent 10 is deformed according to the aforementioned shape of dierecess 27 and into it so that a corresponding local flat region of bore11 is formed (only) at intersection point 13 of two bores 11, 12. Withregard to the resulting increase in strength in the area of intersectionpoint 13, the statements made in this regard concerning the embodimentsaccording to FIGS. 1 through 3 and FIGS. 4 through 5 are also applicablehere accordingly. Female die 24 and trough-shaped recess 27 assist theshaping of the flat region and thus facilitate the development of thedesired inherent compressive stresses in the material area ofintersection point 13.

What is claimed is:
 1. A component, in particular a high-pressure part(10, 10 a) for a fuel injection system, having intersecting bores (11,12), wherein at least one bore (11) of the two intersecting bores (11,12) is designed with a flat region, and the component (10, 10 a) hasinherent compressive stresses in the area of the flat region (16, 21,27) of the bore.
 2. The component according to claim 1 having acontinuous bore (11) and a second bore (12) which opens into it at anangle of 90° or essentially 90°, wherein the first continuous bore (11)is designed with a flat region in the direction of opening of the secondbore (12) (FIGS. 2 and 5).
 3. The component according to claim 1 or 2,wherein the flat region (16, 21, 27) on at least one bore (11) of thetwo intersecting bores (11, 12) is provided only in the area of theintersection point (13).
 4. The component according to claim 1, 2 or 3,the intersecting bores (11, 12) having different diameters, wherein atleast the bore (11) with the larger diameter is designed with a flatregion.
 5. The component according to claim 4, the diameter of the onebore (11) amounting to a multiple of the diameter of the other bore(12), wherein only the bore (11) with the larger diameter has a flatregion, while the bore (12) with the smaller diameter has a circularcross section.
 6. The component according to claim 4 or 5, wherein thebore (12) with the smaller diameter opens eccentrically into the flatregion (16, 21, 27) of the bore (11) with the larger diameter (FIGS. 2,5 and 6).
 7. The component according to one or more of the precedingclaims, wherein the dimensions of the flat region (16, 21, 27) arelarger than the diameter of the smaller bore (12) but are smaller thanthe diameter of the larger bore (11).
 8. A method of producing acomponent according to one or more of the preceding claims, wherein atleast one bore (11) of the intersecting bores (11, 12) which initiallyhave a circular cross section is flattened by non-cutting shaping of thecomponent (10, 10 a).
 9. The method according to claim 8, wherein theshaping is performed on the partially shaped component (10, 10 a). 10.The method according to claim 8 or 9, wherein shaping to produce theflat region (16, 21, 27) is performed by a pressure acting on thecomponent (10, 10 a) from the outside.
 11. The method according to claim8, 9 or 10, wherein shaping to produce the flat region (16, 21, 27) isperformed by a pressure acting on the component (10, 10 a) via a ram(18, 22) approximately at the location (19, 20) of the outer lateralsurface of the component (10, 10 a) where the two bores (11, 12)intersect in the interior.
 12. The method according to claim 11, whereinthe acting pressure is applied by a ram (18, 22) whose dimensionscorrespond approximately to the desired contours of the flat region (16or 21) to be produced.
 13. The method according to claim 11 or 12,wherein the acting pressure is applied by a ram (18) having arectangular cross section (FIGS. 1 through 3).
 14. The method accordingto claim 11 or 12, wherein the acting pressure is applied by a ram (22)having a circular cross section or an essentially circular cross sectionwhich is directed at an acute angle to the opening bore (12) at thedesired location of the flat region(21) to be produced (FIGS. 4 and 5).15. The method according to one or more of claims 8 through 14, whereina female die (24) is inserted into the bore (11) which is to beflattened and has a recess (27) corresponding to the desired contours ofthe flat region at the location (13) which corresponds to the locationof the (subsequent) flat region and then non-cutting shaping of thecomponent (10) is performed (FIGS. 6 and 7).